Optical rheometry of multicomponent polymer liquids

Fuller, Gerald G.

doi:10.1002/masy.19950980190

Cited by 4 publications

(4 citation statements)

References 11 publications

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“…1 Among all the optical phenomena, birefringent responses arising from flow-induced anisotropy are one of the most accessible optical indicators of the structural properties. 2 For measurements, birefringence visualizes different refraction indices between the ordinary and extraordinary axes and can be visualized using polarized microscopy if the materials are non-opaque. 2,3 Well-established techniques, such as the Berek compensator and its variants have been used to quantify static or slowly-varying birefringence.…”

Section: Introductionmentioning

confidence: 99%

“…2 For measurements, birefringence visualizes different refraction indices between the ordinary and extraordinary axes and can be visualized using polarized microscopy if the materials are non-opaque. 2,3 Well-established techniques, such as the Berek compensator and its variants have been used to quantify static or slowly-varying birefringence. In contrast, in many manufacturing processes, transient birefringent responses are of critical importance to capture the evolution of internal structures during material deforming or phase change, which is key to the resulting properties.…”

Section: Introductionmentioning

confidence: 99%

“…From these measurements, we predicted the morphological evolution in the filament along the spinning direction using a physical constitutive framework based on tube models under complex flow conditions. 2,22 We hereby derive a more comprehensive structure-originated dynamic without performing complex scattering-based structural analysis. Outputs from this study can help accurately predict the evolution of fibers in a more general and scaled-up spinning scenario.…”

Section: Introductionmentioning

confidence: 99%

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Rapid in-situ quantification of rheo-optic evolution for cellulose spinning in ionic solvents

Du¹,

Páez²,

Otero³

et al. 2023

Preprint

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It is critical to monitor the structural evolution during deformation of complex fluids for the optimization of many manufacturing processes, including textile spinning.However, in situ measurements in a textile spinning process suffer from paucity of non-destructive instruments and interpretations of the measured data. In this work, kinetic and rheo-optic properties of a cellulose/ionic liquid solution were measured simultaneously while fibers were regenerated in aqueous media from a miniature wet spinline equipped with a customized polarized microscope. This system enables to control key spinning parameters, while capturing and processing the geometrical and structural information of the spun fiber in a real-time manner. We identified complex flow kinematics of a deformed fiber during the coagulation process via feature tracking methods, and visualized its morphology and birefringent responses before and during regeneration at varying draw ratios and residence time. Meanwhile, a three-dimensional physical rheological model was applied to describe the non-linear viscoelastic behavior in a complex wet-spinning process incorporating both shear and extensional flows. We subsequently compared the birefringent responses of fibers under coagulation with the

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Rapid in-situ quantification of rheo-optic evolution for cellulose spinning in ionic solvents

Du¹,

Páez²,

Otero³

et al. 2023

Preprint

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show abstract

“…This set-up, very similar to that of ref. [9] (see also [10], [11]), leads to a detected intensity at 50 kHz: I ∼ = I 0 sin(2δ) sin ϕ, where ϕ is the phase delay due to the sample birefringence, δ the angle between the optical axis ν and the magnetic field H. We neglect here the small contribution of the sample dichroism to I; it is evaluated to 3% of I from a measurement of the signal component at 100 kHz. I 0 is a reference intensity related to the laser power, to the tuning of the PEM and to the transmission coefficients of the sample in the directions parallel and perpendicular to ν.…”

mentioning

confidence: 99%

Magneto-vortical birefringence in a ferrofluid

et al. 1996

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Trends in polymer chemistry 1995

et al. 1996

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Polymerization reactionsDuring 1995 remarkable progress was made in controlled polymerization, especially in "living" radical and transitionmetal-catalyzed polymerization reactions. The breakthroughs achieved in 1995 will further stimulate the design of novel polymeric materials, which offer attractive potential for industrial applications and convert well-known monomers into a wide variety of new materials.In contrast to early generations of multi-site Ziegler-Natta catalysts, developed on the basis of "trial-and-error" research, modern metallocene catalysts contain essentially one type of catalytically active center, which can readily be fine-tuned to produce extraordinarily uniform homo-and copolymers. At present, metallocene structures, especially ligand substitution patterns, are tailored to control polymer microstructures, molecular weights, end groups and morphology development with unprecedented precision. Several reviews and books, published on the occasion of the 40th anniversary of Ziegler-Natta catalysis, present overviews on metallocene catalyzed polymerization [ 1-61. Basic correlations between metallocene structures and polymer properties have been identified, eliminating drawbacks of early metallocene catalyst generations. For instance, substantially increased molecular weights that are of interest for commercial applications of polypropylenes are obtained when a methyl substituent is introduced in the 2-position of metallocenes containing silylene-bridged bisindenyl ligands, while substituents in the 4-position as well as benzannelation promote higher catalyst activities 171. In the case of MAO-activated Me2Si(2-me-benz-(2)ind)2ZrC12 the 2-methyl substituent prevents chain termination via hydride transfer to propene monomer and promotes P-hydride elimination. When monomer is involved exclusively in chain propagation, molecular weights -reflecting the ratio of chain propagation to chain termination ratedepend upon monomer concentration and increase significantly with increasing monomer concentration. It is also possible to improve polymer properties, e.g., stiffness and optical transparency, as a function of metallocene structures and to reduce the contents of low molecular weight fractions [8]. Novel heterogenized metallocene-based catalysts were introduced successfully in gas-phase polymerization [9]. In 1995 the focus in metallocene catalyst development was on new catalysts and processes for controlled olefin copolymerization such as ethene/cycloolefin [lo, 111, ethenejstyrene [12, 131 and ethenell-olefin, including long-chain I-olefins, which are known to give poor incorporation into polyethylene with conventional Ziegler-Natta catalysts [14-161. Moreover, metallocene catalysts in situ copolymerize vinyl-terminated polyethyleneresulting from chain termination via Fax: +49-761-2034709 Acta Polymer., 47, 131-140 (1996) 0 VCH Verlagsgesellschaft mbH, D-6945 1 Weinheim, 1996hydride eliminationwith ethene to produce long-chain branched polyethylenes containing 1-3 CH branching groups per 10 000 CH...

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Optical rheometry of multicomponent polymer liquids

Cited by 4 publications

References 11 publications

Rapid in-situ quantification of rheo-optic evolution for cellulose spinning in ionic solvents

Rapid in-situ quantification of rheo-optic evolution for cellulose spinning in ionic solvents

Magneto-vortical birefringence in a ferrofluid

Trends in polymer chemistry 1995

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